As the dissemination of a 3 dimensional television (3DTV) is raging, a transmission of a 3D image content performed by a digital broadcasting as well as the dissemination of the 3D image content performed by a storing media is vitalized.
In general, a 3 dimensional image provides a 3D effect using a principle of stereo vision of two eyes. Since a human feels perspective via parallax of two eyes, in other word, binocular parallax due to a space between two eyes apart from each other about 65 mm, the 3D image may provide the 3D effect and the perspective in a manner of providing an image, which makes a left eye and a right eye see a related plane image, respectively.
The 3D image display method includes a stereoscopic technique, a volumetric technique, a holographic technique, and the like. In case of the stereoscopic technique, it provides a left view image supposed to be watched by a left eye and a right view image supposed to be watched by a right eye. The stereoscopic technique enables to recognize a 3D image effect in a manner of making the left eye and the right eye watch the left view image and the right view image respectively using a polarized glasses or a display device itself.
In case of a stereoscopic 3D image content, if two similar images having viewpoints different from each other are transmitted, the stereoscopic technique uses a technique that a receiver displays a 3D image using the two images. In case that the 3D image is displayed by the receiver, a 3D image is provided in a manner that the binocular disparity occurs due to a disparity between a left image and a right image.
In this case, the disparity corresponds to a horizontal distance difference between a pixel of a left image and a pixel of a right image indicating a single pixel of a 3 dimensional image.
In order to implement 3 dimensional display of a glassless mode, study on a method of playing a multiview image is in progress. The multiview image is played in a manner of receiving an input of two or more images or is displayed on a screen in a manner of synthesizing images of a virtual view using the inputted images.
In a current 3DTV receiver, a viewer can watch a limitative 3D image of a fixed view only. Yet, an ultimate objective of 3D image broadcasting is to enable a viewer to freely select a preferred view. Hence, study and research on various fields such as multiview broadcasting, a glassless 3DTV and the like to implement the objective are in progress.
A TV should be operable while a viewer is watching broadcasting or an image. According to a legacy art, if a user operates a TV in the middle of watching a 3D image, a case that a position (depth) on which an OSD (on screen display) is displayed vitiates a depth of 3D broadcasting or a 3D image may occur.
Meanwhile, a closed caption is one of TV character multiplex broadcast services and is used for a caption service for a hearing handicapped person. The closed caption is widely used as much as 70% of big 3 television prime time programs of the United States. When the closed caption is displayed on a 3DTV, it is necessary to display the caption on a position (depth) according to a relationship between 3D broadcast or a 3D image and the caption to smoothly display the caption.
Yet, according to a related art, since a scheme of defining a depth of a caption is not proposed, a case that 3D broadcasting or a 3D image and a caption vitiate mutual 3D effect may occur.